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Cam Timing issue?

2K views 10 replies 3 participants last post by  Polystigma 
#1 ·
I have opened my bike up today for a valve check and possible adjustment.

The, Haynes manual states that at TDC, all cam lobes for cylinder 1 will be pointing up away from the bucket.
This is just not the case. I have the dot and hash mark lined up on the crank.
Both cams have the lines facing inward, and flush with the head.

Basically everything indicates perfect sequence.... except for the cam lobes.

At TDC the only lobes facing up are Intake on cylinder 2, and Exhaust on Cylinder 3.

What may the problem be? Or does one even exist?
 
#2 ·
This may come across like I'm being a smartass, but not the case.
You engine is mounted at an angle, at TDC the lobe will be at an angle. Try rotating the motor again til your marks line up again.
Consider a triumph manual in the future.
 
#5 · (Edited)
If all the lobes were lined up you would have big issues.
I realized that after some long analysis. Thanks for the response though.
The timing is perfect.

Now my next issue appears to be getting a correct reading from a feeler gauge. The angle really throws off my feel, especially on the exhaust side. Be it precurved gauge or straight. And I only have a couple sizes in precurved.
 
#11 ·
This was the key to measurement I discovered.

Using straight blades just does not produce accurate feel. The blade is curving a bunch to get under the lobe, and it is levered against the edge of the head. Totally skews your feel.

I took some pre-curved gauges, and further bent them to 90*.
This allowed me to get the blade in under the lobe. Then push back and forth a 1/2" with my index finger and thumb. Much better feel.

Went with the largest blade that fit and created snug drag. If it fits, it fits. LoL

Numbers for the exhaust came out totally different. Two of my valves are actually too loose, while the rest are in spec!

Cylinder 1
Exhaust
Left .320mm Right .356mm
Intake
Left .152mm Right .178mm

Cylinder 2
Exhaust
Left .330mm Right .305mm
Intake
Left .152mm Right .178mm

Cylinder 3
Exhaust
Left .356mm Right .330mm
Intake
Left .178mm Right .178mm
 
#8 · (Edited)
Bummer, my exhaust valves seem to all be way out of spec.:hmm: Engine has 12K miles on it.

I believe to have done good measurements. By feel, I went with what produced a smooth "stutter". If pulling back and forth produced a coarse "stutter", I called it too tight.

Cylinder and cam lobe orientation from left to right, when in normal riding position.

Measurements...

Cylinder 1
Exhaust
Left .279mm Right .229mm
Intake
Left .152mm Right .178mm

Cylinder 2
Exhaust
Left .229mm Right .220mm
Intake
Left .152mm Right .178mm

Cylinder 3
Exhaust
Left .229mm Right .203mm
Intake
Left .178mm Right .178mm

What gives?
 
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